1. Field of the Invention
This invention relates to a two compartment type syringe for dosing the human body with a liquid medicament or nutrient and more particularly, it is concerned with an improved syringe comprising two separated compartments each holding a medicament component and capable of rapidly mixing the medicaments during dosing and carrying out very sanitary dosing.
2. Description of the Prior Art
A syringe capable of previously filling a container with a liquid medicament or nutrient, storing it and using the container itself as an injector in a simple manner has been well known as disclosed in Japanese Utility Model Laid-Open Publication Nos. 79539/1982 and 2343/1984, Japanese Patent Laid-Open Publication Nos. 76390/1973, 16489/1973, 149894/1977, 120166/1984, 501193/1985, 502099/1986, 502086/1989 and Japanese Patent Publication No. 25389/187.
In addition, examples of injectors wherein two kinds of medicaments, for example, a medicament and a solvent, or a liquid medicament and another liquid medicament are stored and mixed or dissolved during dosing have been disclosed in Japanese Patent Laid-Open Publication Nos. 11691/1976, 22391/1977, 61755/1983, 212453/1983, 155264/1984, 72561/1985, 48377/1986, 5357/1987, 5973/1990, 82476/1981 and 96762/1982, Japanese Utility Model Publication Nos. 14465/1974 and 22315/1979 and Japanese Utility Model Laid-Open Publication Nos. 58446/1990 and 29145/1991.
An example of a two compartment type syringe of the prior art is shown in FIG. 15 and FIG. 16, in which two compartments are partitioned by a first sealing stopper 33 and medicaments stored in the two compartments can be mixed when dosing. That is, one end of a cylinder 29 comprises an open end 31, provided with, at the circumference thereof, a finger touching flange 32. The other end 30 is narrowed and sealed by a rubber stopper 38. The first sealing stopper 33 and a second sealing stopper 34 are disposed within the cylinder 29 to be in intimate frictional contact with the inner wall of the cylinder to partition the cylinder into a first compartment 35 and second compartment 36, where a powder medicament 30 is held in the first compartment 35 and distilled water is held in the second compartment in an example as shown in the Figure. Nearly at the central part but toward the narrowed end of the cylinder 29, a bypass part 37 is provided. When dissolving and mixing medicaments, the second sealing stopper 34 is moved by a plunger (not shown) toward the narrowed end and the first sealing stopper 33 is thus moved via distilled water to a position of the bypass part 37 at the narrowed end, as shown by a chain line in FIG. 15, whereby the distilled water in the second compartment 36 flows into the first compartment 35 and mixes with the powder medicament 30 in the first compartment 35 to dissolve the medicament in the distilled water and to prepare a liquid medicament. As shown in FIG. 16, the cross section at the bypass part is designed in such a shape that the outer circumference and inner wall of the cylinder are projected outward with the same thickness at the bypass part.
The prior art, as described above, aimed at mainly improving means for mixing two medicaments in a syringe and had no consideration of a problem of preparing a medicament in a container with a same shape. That is, the syringe having the shape as shown in FIG. 15 and FIG. 16 has the disadvantages that a large volume is required as a space for storage of the container in the process of preparing a medicament, etc. and the workability in adapting the first sealing stopper after filling the powder medicament and adapting the second sealing stopper after filling the second compartment with distilled water is not good, thus resulting in a sanitary problem.